Stabilized aromatic amine-gasoline mixtures



Patented May 8, 1951 "STABIBIZEDLAROMATIC AMmE-GAS'OLINE MIXTURES sWilliamJ. -iswecney, :Summit, TN. 1., :assignor sto StandardOiLDevelopmcnt Company, a corporation ofi'llelaware No Drawing. Application-March'25, 1948,

' Serial No. 17,110

' sol-aims. (c1.,44 7.4)

i1 invention-relates -;to :the .-;stabilization [of aromatic amines against :deterioration by :discoloration-etc, during-storage. ,Itisparticularl-y directed to :the :-stabilization of aromaticwaminehydrocarbon; mixtures, ,such: as gasolinaandis a continuationeinepart 10f .Serial No. 508,394, :filed October 30, 194,3,lnW-;aban'doned.

:Aromatic iamines :such :as aniline, :toluidine, Xylidine, etc.,.:aare:normallyssubstantially colorless when freshly prepared izor freshly @Jdistilled, :but tend (to; darken in -,color ,dur n; sstorage, the desirable :results being rgreatly accelerated y storagezat elevated temperatures.

The :obiect ao-f the tfpresent invention is :to

stabilizeasuchzaromaticaamineseagainstdiscolorationsanditoistabilizeltheir gasoline fuel blends against gum deposition during storage.

Broadly, therinvention compriseszadding to the aromatic ,amines .a ,smalhamount. of a stabilizer comprising an alkyl phenol containingmotimor-e than two alkyl, groupaat least ,one of which is in the ortho'position (in -respect-to "the hydroxyl group).,.alone or togetherriwith. a sulfur-contain ingrstabilizer.

Thelph'eno'l ,to .be .usedshon'l'd usually :contain less than about 22, and preferably less than 10, carbon atoms in any one alkyl group, and a total of less than 25, preferably less than 12, alkyl carbon atoms in any one molecule. Dialkyl phenols are preferred. Some specific examples are: 2- tertiary butyl p-cresol, mixed tertiary butyl oresols, 2-methyl p-cresols and other xylenols as well as commercial xylenol products containing large amounts of isomers alkylated in the o-position, petroleum phenols (which are mostly monoand di-alkylated phenols ranging from 2.6 alkyl Cs and averaging about 4 alkyl Cs per molecule, with a small amount of alkyl ether derivatives of such phenols, a large amount of such phenols being alkylated in at least one ortho position), o-cresol, Z-isopropyl p-cresol, Z-tertiary amyl p-cresol, Z-secondary amyl p-cresol, o-wax phenol, 2-tertiary butyl B-methyl phenol, 2-

isopropyl 6-methyl phenol, o-isopropyl phenol,

o-tertiary butyl phenol, Z-tertiary butyl 4-ethyl phenol, etc. Polynuclear phenols may also be used.

As the optional auxiliary stabilizer, various types of sulfur-containing materials may be used. One class comprises organic sulfur compounds, preferably of the aryl mercaptan type. Such compounds may, for instance, have the general formula RXH in "which R is an aromatic, preferably an alkyl aromatic hydrocarbon radical, and X is an atom selected from the group consistingof sulfur, rselenium, and 'tellurium. Although in such compounds it is preferable that R-be a vmononuclear aromatic radical, :i. e, -:one. derived from benzene,,poly-n,uclear compounds mayalso be used such as those derived from naphthylene and the like. As mentioned.above,.it ispreferable that the aromatic group, R contain one or more alkyl substituents attached to the aromatic nucleus, and in generalitisgpreferable that the radical R contain from 1'to25; alkyl carbon atoms, preferablyl to 5-alkyl-carbon1atoms. One particular sulfur-containing stabilizer whichfhas been found particularly satisfactory is parathiocresol which has the formula CHsCoHeSH. 'Other compounds which may be used include ethylthio- :phenol, :propylthiophenol, .various butylthio- .phenolaasuchsas theparatertiarybutylthiophenol, 12,4 -dimethylr6-,tertiary :butyl thiophenol, etc, as wellas highenalkylzphenolae g.,-:waxthiophenols (in which:an ;a1kyl.group corresponding to the Wax hydrocarbon :molecule is attached to the thiophenol nucleus) Otherasulfur. materials. include thiophene and alkylaterliderivatives:there- .of, *sulfurized :mineral oils, carbon disulfide, Xanthates, elemental sulfur, etc.

Although the amount of the main and optional auxiliary stabilizers to be used may vary according to the intended duration of storage and the temperature of storage, as well as according to the particular aromatic amine and the particular stabilizers used, in general about 0.01% to 1.0% of either stabilizer will be sufficient, and usually about 0.05% to 0.5% by weight of stabilizer will be found most practical for giving satisfactory results.

Although the invention i intended to apply broadly to the stabilization of any type of aromatic amines, it is believed particularly applicable to alkaryl amines, especially those having from 1 to 3 alkyl carbon atoms. The invention has been found very successful for the stabilization of xylidine, either the pure separate isomers, or mixtures thereof. Other alkaryl amines which may be stabilized include the toluidines, ortho, meta or para, or mixtures thereof, the several ethyl anilines, cumidine (which is isopropyl aniline), etc. Dialkyl-ated and trialkylated aryl amines are preferred. Although the invention is particularly applicable to such alkaryl amines, it may also be used for stabilizing aniline, naphthylamines, and the various derivatives of aniline in which either or both of the hydrogens of the amino group are substituted by hydrocarbons, i. e., either alkyl or aryl groups, e. g., in N-monomethyl aniline, N-dimethyl aniline, N-monoethyl aniline, etc. Thus although the invention is particularly applicable to alkaryl primary amines, other amines such as secondary and tertiary amines may also be used.

The various above described aromatic amines may be used alone a for manufacturing dyes or together with a diluent, such as a hydrocarbon solvent, e. g., naphtha, gasoline for use in motor fuels, aviation fuels, etc. Such diluents may be present in amounts ranging from only a few per cent up to 10, 20 or even 100 times the volume of the aromatic amine.

In carrying out the invention, it is preferred to add the stabilizer(s) to the aromatic amine as soon as the latter has been prepared, or immediately after distillation.

The following experimental data will illustrate the advantages of the invention:

A grade 100/130 aviation gasoline containing 1.0% of two different samples of xylidine, 4-6 ml. of lead tetraethyl and 0.8 lb. /5000 gal. of mixed tertiary butyl para cresol, including 2-tertiary, butyl-4-methyl phenol was subjected to various gum tests and the N2 bomb test with the following results:

Gum Content, Mg./l ml. Xylidine Inhib- :1 Bomb Test Sample Glass Copper -Hr. lfi-Hr. 2

dish dish Army Army 3 4 7 13 Does not pass.

2 2 6 7 Pass.

2 6 7 17 Does not pass.

1 l 5 13 Pass.

ing a mononuclear aromatic amine having from 1 to 3' alkyl carbon atoms and a stabilizmg amount of a 2,4-dialkyl phenol in which one alkyl substituent is a radical of the group consisting of primary, secondary and tertiary alkyl radicals and the other alkyl substituent is a radical of the group consisting of primary and secondary alkyl radicals.

2. A composition comprising gasolin containing a mononuclear aromatic amine having from 1 to 3 alkyl carbon atoms and a stabilizing amount of a 2,4-di-alkyl phenol having a maximum of about 25 carbon atoms and in which one alkyl substituent is a radical of the group consisting of primary, secondary and tertiary alkyl radicals and the other alkyl substituent is a radical of the group consisting of primary and secondary alkyl radicals.

3. A composition comprising gasoline containing at least 1% of a mononuclear aromatic amine having from 1 to 3 alkyl carbon atoms and about 0.0001 to 0.01% by volume of 2,4-dialkyl phenol in which one alkyl substituent is a radical of the group consisting of primary, secondary and tertiary alkyl radicals and the other alkyl substituent is a radical of the group consisting of primary and secondary alkyl radicals.

4. A composition comprising gasoline containing at least 1% of xylidene and about 0;0001 to 0.01% by weight of Z-tertiary butyl paracresol.

5. A composition comprising gasoline containing xylidene and a small amount of mixed monotertiary butyl cresols having one of two alkyl groups in the ortho position with respect to a hydroxyl group to stabilize the composition.

WILLIAM J. SWEENEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A COMPOSITION COMPRISING GASOLINE CONTAINING A MONONUCLEAR AROMATIC AMINE HAVING FROM 1 TO 3 ALKYL CARBON ATOMS AND A STABILIZING AMOUNT OF A 2,4-DIALKYL PHENOL IN WHICH ONE ALKYL SUBSTITUENT IS A RADICAL OF THE GROUP CONSISTING OF PRIMARY, SECONDARY AND TERTIARY ALKYL RADICALS AND THE OTHER ALKYL SUBSTITUENT IS A RADICAL OF THE GROUP CONSISTING OF PRIMARY AND SECONDARY ALKYL RADICALS. 